Interstate Highways vs. US Highways: An Overview and Comparison

The history of road transportation in the United States spans several decades, from the early 20th century to the modern highway systems we have today. Two key types of highways, Interstate Highways and US Highways, have played a crucial role in connecting America. This article aims to help you understand the differences and significance of these two systems.

Federal-Aid Road Act and Early Developments

The journey to our modern highway systems began with the 1916 Federal-Aid Road Act, introduced by President Woodrow Wilson. This groundbreaking legislation allocated $75 million over five years to build or improve federal roads, effectively starting the federal effort in highway construction. At the time, the United States was home to over 21 million horses, 3.5 million cars, and 250,000 trucks, with the BPR managing to construct only a fraction of the total funds allocated.

The 1919 Lincoln Highway Investigation

In 1919, future President Dwight Eisenhower embarked on a journey from Washington, DC, to San Francisco along the Lincoln Highway. This road was formed by combining various public and private routes, but the trip proved to be a logistical nightmare, highlighting the need for improved and more efficient routes. This journey marked the beginning of a new era in crossing the United States via road.

US Highway Numbering System and Early Developments

By 1926, the US Highway numbering system was established, defining the routes we see today. Over time, these highways evolved, with many becoming multi-lane roads. However, they retained many of the limitations of older roads, including difficulties navigating cities and rural areas. US highways were supplemented by state highways in the 1930s, but these often lacked federal funding and were notably inferior in design.

The Birth of the Interstate Highway System

President Eisenhower's vision for a new, safer roadway system led to the 1956 Federal-Aid Highway Act, which established the Interstate Highway System. This revolutionary system aimed to provide a high-speed, limited-access network connecting all states. The AASHO, alongside the U.S. Bureau of Public Roads and the National Academy of Sciences, began to establish rigorous design standards through the National Cooperative Highway Research Program, ensuring that the highways would be safe, efficient, and enduring.

Construction and Evolution of the Interstate System

The construction of the Interstate Highway System was a mammoth undertaking, taking 36 years to complete the 46,000 miles of highways. The first segments began construction in 1956, reaching Glenwood Springs, Colorado, by 1992. This endeavor is one of the greatest engineering feats in history, ensuring not only the safe and speedy movement of people but also significant economic advantages. The Interstate Highway System connects states and carries the majority of traffic and freight.

Interstate Highways and US Highways: Key Differences

Understanding the differences between Interstate Highways and US Highways is crucial. Generally, Interstate Highways are fully controlled-access highways, meaning the only entrances and exits are via on- and off-ramps. In contrast, US Highways are often multi-lane and can still have intermittent traffic signals, driveway approaches, or steep grades. Many US Highways have been upgraded to meet the standards of Interstate Highways but retain some of the limitations that prevent them from being called true interstates.

Current States and Highway Systems

Today, all states except Alaska have Interstate Highways. Hawaii uses "H" as the prefix, while Alaska has a high-speed highway system with "A" as the prefix. However, these highways are not fully controlled access and often remain two-lane wide. This highlights the importance of distinguishing between these highway systems and understanding their unique roles in the interconnected American transportation network.

Conclusion

The Interstate Highway System and US Highway System have each played a pivotal role in the United States' transportation network. The Interstate system represents an advanced engineering achievement, designed to ensure safety and efficiency, while the US Highways continue to serve as critical connectors within states and regions. The transportation infrastructure in the United States is a testament to the ongoing efforts to improve and maintain this vital network.